This invention concerns a process for cutting workpieces by a laser beam to remove material by vaporization. In such apparatus, the laser beam is advanced along points forming a predetermined cutting pattern on a workpiece surface.
A widely used method for determining the extent of material removed during controlled cutting involves the use of triangulation type sensors as described in U.S. Pat. No. 5,883,356. These sensors, however, due to their triangulation operating principle, are limited in their ability to reach the bottom of the scoring produced by the cutting device. This is particularly so for narrow, deep penetrations which may be produced by cutting devices such as lasers and cutting knives. Furthermore, due to their offset mounting, these sensors are not well suited to measure the varying penetration depth that occurs during scoring at a specific location. This is especially true if the scoring penetration is in the form of partial perforations or slots. As such, the process does not lend itself to scoring the workpiece in an adaptive control mode, where both depth sensing and cutting are in registry with each other to impinge the same point on the workpiece, during the progression of scoring of the piece.
Accordingly it is an object of this invention to provide a process for laser beam cutting in a manner that provides accurate adaptive process control, single-pass processing, and lower manufacturing costs.